The present invention relates to an article made mainly of polyethylene terephthalate resin, particularly to laminated wall structures of bottles made by biaxial orientation blow molding mainly from polyethylene terephthalate resin.
Products, particularly orientation blow molded bottles, made of polyethylene terephthalate (hereinafter referred to as PET) or PET copolymers are used in large quantities as containers for foods, cosmetics, detergents, etc. because of their outstanding properties in clarity, chemical resistance, gas barrier, rigidity, mechanical strength, and hygienic qualities.
Notwithstanding these superior characteristics, PET products are not necessarily free from drawbacks. For instance, it is hard to give orientation to the neck or bottom of an orientation blow molded bottle. In products of complex design it is impossible to give uniform orientation which is applied to films or it is impossible to heat set orientation completely.
These drawbacks are not inherent in PET per se and can be overcome relatively simply by heat treatment or design modification. However, PET suffers from an inherent, serious drawback in that the gas barrier properties against oxygen are not satisfactory.
This is the reason why PET has been considered to be inadequate for use as containers of juice, beer, etc. which are sensitive to oxygen. PET products having outstanding properties required for containers are limited in their use because of their insufficient gas barrier properties against oxygen.
Nevertheless, there has been a strong desire for PET containers which can be used for oxygen-sensitive contents. Such containers must have outstanding gas barrier properties, while keeping the above-mentioned properties desirable for containers.